Latching relay



Oct. 20, 1931. P. F. SHUEY 1,828,299

LATCHING RELAY Filed DeG. '7, 1928 ATTRNEY Patented ct. 20, 1931 UNITED STATES PATENT OFFICE 4 PAI-UI: F. SHUEY, 0F SWISSVALE, PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSE ELEC- 'VIBIC & MANUFACTURING COMPANY, A. CORPORATION OF PENNSYLVANIA.

LATCHING RELAY Application filed December 7, 1928. Serial No. 324,546.

[My invention pertains, in general, to control relays and, in particular, to a control relay having an armature which is adapted to be latched in both the attracted and re- 5 tracted4 positions.

The principal object of my invention is to provide a relay having a contact-controlling armature which shall not be subject to operation by accidental or transient energization. Ay further object of my invention is to construct va relay having an attractable armature and a positive,` mechanical lock to prevent the movement of the relay armature in either direction and to permit such movement only when desired.

A :further object of this invention is to utilize a thermally-responsive element as a4 latching Imember for maintaining the relay armature in either of its positions.

Further objects of the invention will be# come apparent as the description thereof progresses.

Control relays, as known to the prior art, are subject to the disadvantage that they are liable to be operated by accidental or transient energization. It has often happened furthermore, in systems including a number o'f. control relays adapted to be simultaneously energized, that some of the relays failed to operate when energized and failed to release when deenergized. It has been proposedto employ a relay of the induction-disc type to avoid this'diiiiculty. Induction-disc s, relays, however, are bulky and expensive and it is an object of this invention to provide a substitute which shall be equally effective, very.' much less expensive and smaller in size. In accordance with my invention, I propose to 1 employy a thermally-responsive element such as a bi-metallic strip, having a suitable heating coil, as a latch or stop to prevent the attraction of the relay-armature when the stop o r thermal element is at its normal tcmperature. I propose to utilize thevsame stop to permit attraction of the relay armature and to lock it in the attracted position, as well as to release it therefrom when desired. The details of my invention by which the 505 foregoing results may be accomplished, will ous that numerous other applications exist for such device and the description thereof in connection with a street lighting system is intended merely as an example.

As shown in the drawing, the relay of my invention is adapted to control the connection of an electrical device such as a lamp 10 to a supply circuit indicated at 11-12. Alternating current of commercial frequency or direct current may be supplied to the circuit 11-12 by a generator 13 or other suitable source. An auxiliary, control generator 14 is adapted to be connected to the circuit 11-12 in series with a blocking condenser 14a by means of a switch 15 or other equivalent control apparatus. The function of the auxiliary generator 14 is to supply a hi h-frequency control 'current to the circuit or the operation of a relay such as that illustrated at 16 which is connected in a tuned circuit comprising the inductance 17 and the capacitance 18, across the circuit 11-12. The condenser 14a prevents the How of current from the generator 13 through the generator 14. The function of relay 16 is .to control the energization of the lamp relay indicated generally at 19. The relay 16, obviously may be so designed that an additional inductance such as 17 may be omitted.

The relay 19 comprises a core 20 secured to one arm 21 of an L-shaped bracket 22 which is adapted to be supported from any suitable surface, horizontal or vertical, by any convenient means such as the screw or bolt 23. A magnetizing winding 24 (illustrated diagrammatically in dotted lines surrounding the core), is provided to cause the core 20 to attract an armature 25 which is pivotally supany convenient manner.

A horizontal extension 28 oi the armature is adapted to actuate a flexible contact 29 to cause it to engage a fixed contact when,

the armature of the relay is attracted by the core. rlhe contact members 29 and 30 are secured tothe bracket 2,2 by means of machine screws 31 and insulating washers 32. The projection 27 on the eXtension128 limits the movement of the armature 25 away from the core of the electromagnet of the relay.

A thermal element 33, such as a bimetallic strip, is secured in any convenient manner to the bracket 22, e. g., to the vertical portion 21 thereof, and is provided with a heating coil 31lwhich may preferably be connected in series with the magnetizing coil 24 of the relay. The thermal element 33 is adapted, when at normal temperature, to engage the lower end of the armature 25 to prevent the movement of the armature in response to the energization of the magnetizing coil 2 4.y The stop 33, however, is so designed that, when heated to a predetermined temperature, it is deflected slightly to permit the armature 25 to be attracted by the electromagnet of the relay. When the armature is attracted, however, it will be latched in the attracted position by the projection 35 of the member 33, as a result of the spring action'o the latter. When the latch 33 is heated by the energization of the heating coil 34 to a still higher temperature, it will be deflected suiiciently to withdraw the projection 35 from the path of the armature 25. The armature 25 is thereby released and will be restored to its normal position when the magnetizing coil 24 is deenergized. The armature is restored to its normal position by the weight of the extension 28 thereof and the spring action of the flexible contact 29. lt will be apparent that the member 33 may be so designed that changes in the ambient temperature will not actuate it t0 either of its operative positions.

The operation of the relay of my invention will probably be apparent from the foregoing description thereof, but it is deemed advisable to incorporate a brief description thereoic in connection with the control system for which it was designed.

When it is desired that the lamp 10 be con nected to the supply circuit 11-12, it is necessary to connect the auxiliary generator 14 to the circuit for a predetermined periodof time to energize the relay 16 which, in turn, energizes the heating and magnetizing coils of the relay 19. The heating coil 34, after a predetermined time, causes the latch 33 to be withdrawn from its normal position to permit the armature 25 to be attracted and latched by the projection 35. It will be observed that the latch 33 normally prevents the attraction of the armature 25 as a result of accidental or transient energizations of the magnetizing coil 24. Until the latch 33 has been heated to a temperature at which it xLefaaaee permits the armature 25 to be attracted, the operation of the relay is positively prevented.

Whenthe control frequency has been supplied to the circuit 11-12 and the heating and magnetizing coils of the relay 19 energized for the necessary time interval, the lat'ching member 33 will be deflected slightly so that the armature 25 may be attracted. The movement of the extension 28 of the armature will cause the engagement of the contacts carried by the contact members 29 and 30, to connect the lamp 10 directly to the supply circuit 11-12. As the armature 25 is attracted, however, it deliects the latch 33 further to pass the projection 35 thereof, and when the armature passes the projection, the flexible member 33 is slightly retracted and, by the projection 35, retains the armature in its attracted position. The auxiliary generator may now be disconnected from the circuit and the lamp lO-will remain connect'- ed thereto, receiving its energy from the main supply source, such as the generator 13. Now when it is desired to disconnect the lamp 10 romvthe circuit 11-12, the auxiliary generator 14 isagain connected t'o the circuit to energize the relay 16 for a longer period than before. As a result, the heating coil 34 and magnetizing coil 24 of the relay 19 are again energized from the circuit l1- 12. When the heating coil 34 has been energized for a sufficient length of time, the bimetallic member 33 will be deflected still further and the projection 35 will be Withdrawn from engagement with the armature 25 to permit the restoration thereof to its normal position when the magnetizing and heating coils are deenergized. The cooling of the thermal member 33 is suiciently slow to permit thearmature 25 to be retracted when the relay coils are deenergized by the release of the armature of relay 16, before the 'thermal element 33 returns to its normal position. When the armature 25 is released by the opening of the switch 15 and the consequent deenergization of relay 16, the lamp 10 is vdisconnected from its supply circuit.

The chief advantages of the relay of my invention are its extreme -simplicitv 'and reliability. as well as its unusually low cost. It functions in thevmanner above described to prevent the energization of a remote electrical device as a result of accidental or transient conditions such as inductive surges. It also maintains the device connected to the circuit, although its magnetizing coil is entirely deenergized. It includes, furthermore, means for disconnecting the electrical device from the circuit Whenever such action is desired and reduces to a negligible minimum the-chances for any relay to get out of step with other similar relays simultaneously .en-

details of the relayof my invention will, nov

doubt, occur to those skilled in the art and,

for this reason, I do not wish to be limited coil adapted, when energized, to attract said armature, of a thermally responsive latching member having aheating coil, adapted, when at normal temperature, to prevent the attraction of said armature by said magnetizing coil, when at a predetermined temperature, to permit the armature to be attracted and latched, and,'when at a different temperature, to release said armature. to permit it to return to its normal position.

2. A thermal magnetic relay comprising an armature, a magnetizing coil therefor, a thermally-responsive latch for maintaining said armature in attracted or retracted position and a heating coil for said latch whereby the latch may be actuated to prevent attraction or retraction of said armature and to permit attraction and lretraction thereof.

3. In a relay having an attractable armature, a thermal element for latching said armature in attracted and retracted positions.

4. A relay having an armature and a single stop comprising a' bi-metallic member and a hea-ting coil for maintaining said armature in either the attracted or retracted positions.

5. An electro-responsive device includingr a movable-armature contact means, actuating means there-for, and means for locking the armature in both the open and closed positions in accordance with predetermined time intervals of energization of s-aid electro-responsive device.

6. An electro-responsive device including an attractable armature and a thermallyactuated means for controlling the movenient of said armature from the attracted and retracted positions thereof in accordance with. predetermined time intervals of energization of said electro-responsive device.

7. A control relay comprising a plurality of contact members, a pivotally mounted armature for actuating said contact members, an electromagnet for effecting the operation of the armature, and a bi-metallic latching member for controlling the movements of the armature, said latching member being provided with a heating coil, the energization of which is dependent upon the energization of the electromagnet, said latching member being disposed, when in an unheated condition, to prevent actuation of the armature by the electromagnet, when heated to a predetermined degree to permit free movement of the armature, and when heated to an intermediate degree to retain the armature in its actuated position.'

In testimony whereof, I have hereunto subscribed my name this first day of December PAUL F. SHUEY. 

